Radiation therapy, a common treatment regime for cancer, can cause severe damage to radiosensitive organs, including the bone marrow, the gastrointestinal (GI) tract, and the lung. Toxic effects of radiation on the gastrointestinal system cause symptoms such as nausea, vomiting, diarrhea, electrolyte imbalance, and dehydration. Radiation can also cause pulmonary injury, leading to pulmonary pneumonitis and fibrosis.
Radiation toxicity not only causes devastating effects on the quality of patient life, but can sometimes even be more life-threatening than the primary tumor or cancer. Therefore, it is important to monitor the severity of radiation toxicity in patients during the course of radiation therapy.
Currently, there is no biomarker that indicates whether a person develops radiation toxicity. There is also no biomarker that can accurately determine the radiation dose absorbed by a person having radiation exposure.
The anoctamin (ANO, also known as TMEM16) protein family, which consists of 10 members (ANO 1-10) in mammals, is a family of transmembrane proteins having Ca2+-activated Cl− activity. ANO proteins play a role in various diseases including cancer. It has been reported that ANO1 (also known as TMEM16a) is upregulated in gastrointestinal stromal tumor, as well as in oral and head and neck squamous cell carcinoma. It has been also reported that ANO5 (also known as TMEM16e) mutations in humans cause gnathodiaphyseal dysplasia. In addition, it has been reported that ANO7 (also known as TMEM16g) is selectively expressed in normal and cancerous prostates and regulates cell-cell aggregation.
Anoctamin proteins have not previously been reported as being associated with radiation toxicity.